A river gunboat is a type of gunboat adapted for river operations. River gunboats required shallow draft for river navigation. They would be armed with relatively small caliber cannons, or a mix of cannons and machine guns. If they carried more than one cannon, one might be a howitzer, for shore bombardment. They were usually not armoured. The fictional USS San Pablo described in Richard McKenna's The Sand Pebbles is an example of this class of vessel, serving on the US Navy's Yangtze Patrol. Stronger river warships with larger guns were river monitors.
Imperial German Navy river gunboat SMS Otter c. 1909 during trials on the Weser
HMS Ladybird at Shanghai in the 1920s.
A gunboat is a naval watercraft designed for the express purpose of carrying one or more guns to bombard coastal targets, as opposed to those military craft designed for naval warfare, or for ferrying troops or supplies.
Bramble-class gunboat, built for the Royal Navy in 1886
A model of a type of decked "gun yawl" designed by Fredrik Henrik af Chapman and used by the Swedish archipelago fleet
The screw gunboat USS Alliance, circa 1880
Insect-class HMS Ladybird (with larger-calibre guns installed in 1939)